A water output switch structure of a faucet includes a water output switch structure of a faucet comprising a faucet main body, a water guiding duct, a switch valve, and a positioning unit including an adapter, a locking unit, a water-stopping pad and a water-stopping ring. The switch valve has a valve stick that moves horizontally, so a pulling head of the valve stick would not fall down unexpectedly due to gravity to change the status of water output.